Culinary utensil of fibrous structure and method of making same



Patented Dec.. ,28, 1937 PATENT OFFICE CULINARY UTENSIL F FIBROUS STRUC-TUBE AND METHOD OF MAKING SAME Albert L. Clapp, Danvers, Mass.

No Drawing. Application June 1'], 1933,

- Serial No. 676,401

6 Claims.

This invention relates to plates and other or.

similar culinary utensils constructed of fibrous material and to animproved method of manufacturing such fibrous products and refersparticularly to the manufacture of fibrous plates and other culinaryutensils which possess, for a predetermined thickness or caliper,relatively great stifiness and rigidity.

Fibrous plates and other similar articles here- 10 tofore constructed,whether stamped from the paper directly or from molded pulp, have verylittle of the stiffness and rigidity of the articles they are intendedto replace. Since nearly all plates or molded articles from paper have acaliper of approximately from 10 to 30 points, this lack of stiffnessand rigidity is very noticeable. However, it is desirable to maintainthis low caliper in order to obtain relatively light weight products ofthe desired heat-transfer properties and, at the same time, far moreeconomical and efficient in other respects for manufacturing andselling.

It is one of the objects of my invention to produce these utensils withthe same caliper as plates and other articles now produced from paper,but to greatly increase the rigidity; that is, to approach to a maximumdegree the characteristics of the articles they are to replace. IAnother object of my invention'is to so treat the pulp or paper makingmaterial while the same is being disintegrated in a beater engine or thelike in the wet state in such a manner that when dry, it will have thehereinbefore mentioned stiff and rigid characteristics.

A further object of my invention is to treat the pulp to render itwaterproof for molding articles to be used for cooking or for foodproducts, and to render these articles sufficiently fire-resisting towithstand relatively high temperature when the plates or utensils areused for cooking purposes.

The process of my invention may be carried out in several ways, forinstance, the plates or utensils, may be molded directly from the pulpin wire molds which allow for free passage of water under pressure, orthe pulp may be beaten out in an ordinary beater engine and run over anystandard paper making machine or wet machine, so called.

In carrying out my process, a beater engine may be loaded with pulp orpaper making materials, such as ordinaryground wood-pulp, chemicalpulps, asbestos, and various combinations of these When the pulp isbeaten out to the proper degree of fineness, it is then treated with astiffening agent. The stifiening agent found most suitable for thispurpose is raw starch, such as potato or corn starch.- However, otherstarchy materials may be used to advantage. It has i been founddesirable to mlx-the starch in cold water before adding it to the stockin the beater engine, as this produces a fine milky suspension whichreadily and uniformly mixes with the pulp. Cold water is used, becauseit is important not to cook this starch, since cooked starch does notgive the stiffness desired, as will be hereinafter set forth. After thestarch suspension is thoroughly mixed with the stock, the stock is thensized by any of the well known methods of sizing, such as rosin size,wax sizes, or the like. When the sizing is completed, the stock is thenrun into paper on any of the standard paper making machines and madeinto dry rolls or sheets of a desired caliper. This paper is now readyto be molded into the plates or other articles. Before molding thepaper, it may be tempered, that is, slightly moistened, and then stampedin hot molds or dies designed for the purpose or those which are nowcommonly used for molding paper articles. It is necessary that the moldsbe quite hot, having a temperature of not less than 300 F., orthereabout. It is by means of the hot mold that the starch is modified;'that is, the starch particles which are intimately mixed in the stockburst and swell, which, with the combination of heat and pressure in themolds, cause the finished articles to be rigid and stiff. The effect of'the bursting and swelling of the raw starch particles completely fillsthe interstices and pores of the finished product. Various degrees ofstiffness can be produced by different proportions of starch used in theprepared stock. It has been found in practice that very largeproportions of starch can be added to the stock and retained in thefinished article, thereby producing a correspondingly more rigidutensil. made containing as high as 40% starch; however, 10% to 20% ofstarch gives desirable results.

If it is found desirable to mold the paper cold, it can be tempered in aweak alkaline solution and then molded and pressed in cold dies; andwhen the pulp is dry, it will become rigid and stiff, as the alkalineacts as a medium of modifying the starch. However, this latter processis-not desirable if the paper has been sized to waterproof, as thealkaline reaction affects the waterproofing size in the paper. Thisalternative is utilizable only when a stiff, rigid plate is desired withlittle or no waterproof properties. 4

The hereinbefore described method of treating Products have been itunder heat and mechanical pressure, or by means of an alkaline solution,also renders the finished article'greaseproof, since a film of dry,modified starch permeates the sheet, and the modified or convertedstarch has greaseproofing qualities.

In carrying out my process by any of the well known methods of moldingin wire constructed molds, the procedure is as follows:

The stock may be prepared in the beater in the usual manner, the starchand sizing being added as previously described, well beaten out-to thedesired degree of fineness. This pulp is then diluted with water to aconsistency of about 1%, which is generally necessary in molding stockin wire constructed molds. This stock is then flowed into the molds andpressed or formed into the desired shapes, the molds being soconstructed as to allow free passage of water and to give the desiredshape to the article. When the molding process is completed, the articleis still wet, containing practically 60% water. It may now betransferred into another mold of the same design and held in this shapeunder heat and pressure until dried.- In order to properly convert thestarch as above mentioned, it is necessary to have a heat of not lessthan 300-400 F. or thereabouts. To allow quick evaporation of the water,it may be necessary to have these molds perforated or of reinforced wireconstruction. Pulp articles having a caliper of 30 points will dry inapproximately 15 to 30 seconds; and they have the requisiteheat-transfer properties.

If the articles are molded by the well known method of blowing pulp ontomolds, or by means of sucking the wet pulp onto molds after forming',they may be placed in conveyors and dried at a longer period of time andat a lower temperature; in this case, it has been found that atemperature of about 200-250 and about 30 minutes is suflicient toconvert the starch and to dry the article.

These articles, thus made, are useful for many kinds of plates, dishes,and utensils of substantially all kinds.

When the utensils are to be used for baking or cooking, the stock may becompounded with various proportions of asbestos. For cooking pastry, ithas been found that 20% to 25% asbestos or thereabouts is sufficient;for higher temperatures, 50% to 85% asbestos.

The plates and utensils, as described, may be coated with desired wellknown compounds in order to improve their appearance. These coatingcompounds are preferably of such character as not to affect foodproducts in any way.

Examples of furnishes which have proved to be practical for cookingutensils are as follows:

Pounds 1. Wood-pulp 60 Sulphite 15 Asbestos 30 To this may be added 10to 20 pounds of corn starch mixed in sufiicient water to allow a finesuspension. About five pounds of rosin size may then be added. Afterthoroughly mixing and beating the above material into the desiredfineness, about five pounds of aluminum sulphate may be added toprecipitate the rosin size. This furnish is suitable for running on apaper machine, either a Fourdrinier or a cylinder machine, the caliperof the finished stock being about from the stock with unmodified starchand modifying 10 to 30 points. The same may be tempered and molded underheat and pressure.

2. 400 lbs. of sulphite 600 lbs. of asbestostreated with from 10 to 20pounds of starch and sized. The paper may be run to the desired caliper,and molded under heat and pressure. This furnish is suitable for cookingutensils where great heat is required, such as for roast meats, bakingfish, or the like.

Pounds 3. Wood-pulp 60 Fine sawdust about from 20 to 40 mesh 15 To thismay be added about 25 pounds of asbestos treated with from 10 to 20pounds of starch sized with about 5 parts of rosin size and 5 parts ofalum. This furnish may be used where the article is molded directly fromthe pulp in a liquid suspension. In molding pulp articles in thismanner, it has been found necessary to have a rather free stock, thatis, a stock from which the water is easily released.

In order to accomplish this, it has been found desirable to add theabove proportion of sawdust, which gives the pulp the desired freeness.This furnish may be suitable for baking pies and pastry.

Pounds 4. Asbestos 85 Sawdust 15 Parts Starch 10 to 20 Rosin size andalum 5 be used and are not intended to be construed as a limitation ofmy invention.

In my process it will be noted that the starch is the medium forproducing the stiffness and rigidity and also imparts thegrease-resisting properties, and should not be confused with the methodsof sizing paper with the Well known method of cooking starch. The cookedstarch size does not give the desired stiffness and rigidity, nor doesit impart the slightest degree of grease-resisting properties; it is byincorporating the raw starch in the stock in the beater in theproportion mentioned that this rigidity and grease-proofness isobtained. Cooked starch sizes are unsatisfactory because they aremodified before being added to the stock. It is the bursting ormodifying of the raw starch particles that renders the finished productstiff and much stronger than is possible in the case of ordinary starchsizes. Furthermore, it is possible to introduce into the beater a muchlarger proportion of starch than could be used by the cooked starch sizemethods, thus obtaining various degrees of rigidity and strength.Whenever 15% or 20% is used, it is possible to produce a very highluster finish.

The term "starch or starchy materials as used in the specification andclaims is intended to include such materials as tapioca, sago andcereals such as fiour, fine corn meal, or in general, any material whichmay produce the bursting ac tion hereinbefore described. The term pointsis used herein as it is customarily used in the paper-making industry-toconnote thickness in thousandths of an inch.

I claim as my invention:

1. A culinary utensil shaped and adapted to hold foodstuff duringcooking and baking operations and of a relatively stiff and rigid moldedstructure comprising interfelted fibrous material of a thickness notexceeding about 0.030

inch, the pores of which contain swelled starch particles derived fromrawstarch modified to a swelled condition in situ in the pores, saidstarch being present in the amount of at least based on the dry weightof the fibrous material, and said amount of starch serving to stiffensaid structure sufficiently to keep its molded shape when handled and torender said structure substantially greaseproof.

2. A culinary utensil shaped and adapted to hold foodstuff duringcooking and baking.operations and of heat-withstanding, comparativelythin, relatively stiff, molded, fibrous structure of a wall thicknessnot exceeding about 0.030 inch and comprising asbestos and alkalimodified and swollen starch, said starch having been modified andswollen in situ in such structure and being present in the amount of atleast about 10%, based on the dry weight of fibrous material, and saidamount of starch serving to stiffen said structure suificiently to keepits molded shape when handled and to render said structure substantiallygreaseproof.

3. A culinary utensil shaped and adapted to hold foodstufi duringcooking and baking operations and of heat-withstanding, relativelystiff, molded fibrous plate structure of a thickness not exceeding about0.030 inch and comprising asbestos and alkali modified and swollenstarch, said starch having been modified and swollen in situ in suchstructure and being present in the amount of at least about 10%, basedon the dry weight of fibrous material, and said amount of starch servingto stiffen said plate structure sufiiciently to keep its molded shapewhen handled and to render said structure substantially greaseproof.

4. A method of making relatively stifi, molded, fibrous culinaryutensils shaped and adapted to hold foodstuff during cooking and bakingoperations, which comprises mixing unmodified starch and a fibrous pulpin an aqueous vehicle to produce a mixture containing at least about 10%starch, based on the dry weight of the pulp, formingsaid mixture intosuch molded culinary utensil of a wall thickness not exceeding about0.030 inch, and modifying the starch included in the structure by moistheat and pressure, thereby stiffening such structure sufficiently tokeep its molded shape.

5. A method of making relatively stiff, molded, fibrous culinaryutensils shaped and adapted to hold foodstuff during cooking and bakingoperations, which comprises mixing unmodified starch and a fibrous pulpin an aqueous vehicle to produce a mixture containing at least about 10%starch, based on the dry weight of the pulp, forming said mixture into'such molded culinary utensil of a wall thickness not exceeding about0.030 inch, and modifying the starch in said structure in the presenceof alkali and moisture and drying such structure, thereby stiffeningsuch structure sufficiently to keep its molded shape.

6. A method of making thin but still fibrous culinary utensils shapedand adapted to hold foodstuff during cooking and baking operations,which comprises mixing with fibrous pulp in an aqueous vehicle'rawstarch in the amount of at

